The invention relates to a method for measurement of a two-wheeled vehicle frame, in which an essentially U-shaped measurement bracket with two limbs and an upper crossbar is inserted, centered, into a retaining hole which is at right angles to the longitudinal axis, and is moved to a fixed angular position, an optically acting component is inserted into a headstock of the two-wheeled vehicle frame, and a relative position between the measurement bracket and the optical component is fixed by means of a beam path between the measurement bracket and the optically acting component.
The invention also relates to a measurement device for measurement of a two-wheeled vehicle frame having an essentially U-shaped measurement bracket, which can be centered, can be fixed in a fixed angular position, and has two limbs and an upper crossbar, and having an optically acting component, which can be inserted into a headstock of the two-wheeled vehicle frame, in order to form a beam path between the measurement bracket and the optically acting component.
Numerous methods and measurement devices of this type are known.
EP 0 491 369 B1 discloses a rail which is inserted in a headstock and whose longitudinal axis extends at right angles to the direction of the longitudinal axis. A laser which interacts with reflectors fitted to the bracket can be moved on the rail.
According to EP 0 704 671 A2, image recorders, which are aimed at an arrangement, which is inserted into the headstock and has two balls arranged axially one above the other, are inserted into the crossbar of the measurement bracket, in the region of the limbs. The connection vector between the two balls can be determined uniquely by means of photogrammetric evaluation methods, so that it is possible to define the relative position of the headstock axis with respect to the mounting axis of the bracket.
The known methods and apparatuses have the common feature that the data relating to the two-wheeled vehicle frame is determined exclusively on the basis of the optical measurements. The known arrangements are relatively complex, so that it is financially impossible to purchase them for relatively small workshops. Any measurement which is required per se on a two-wheeled vehicle frame which might have been damaged in an accident is thus frequently not carried out, for financial reasons, and leads to danger to the user of the two-wheeled vehicle, in particular of a motor cycle.
The invention is based on the problem of allowing a two-wheeled vehicle frame to be measured using a simpler and lower-cost apparatus, as well.
Against the background of this problem, the method mentioned initially according to the invention for measurement of a two-wheeled vehicle frame is characterized in that the optically acting component is mounted in the headstock without any play but such that it can rotate, using an adjustable-height insert which is provided with a first scale, the crossbar is provided with a horizontal marking and with a central horizontal second scale, the crossbar is provided with an optically acting surface, whose distance from a plane, which runs parallel to this surface through the center of the retaining hole is defined, the optical component is provided with a marking which allows a mechanical distance measurement to a marking on the measurement bracket and whose distance from the optical axis of the beam path is defined, the distance between the horizontal marking on the crossbar of the measurement bracket and the center axis of the retaining hole is defined, and in that the parameters which are required for the measurement are determined using the defined constant dimensions, by means of mechanical measurements and optical determinations.
The method according to the invention thus provides for evaluation of the necessary optical measurements using data which is obtained from defined constant dimensions of the apparatus and from mechanical measurements, in particular length measurements. Using the constant dimensions and the measurements which can be obtained mechanically with sufficient accuracy, it is thus possible to keep the complexity for the optical measurements low, so that a simple and low-cost apparatus for measurement of the two-wheeled vehicle frame is made possible.
According to the invention, and in particular to carry out the method according to the invention, the measurement device of the type mentioned initially is characterized in that the optically acting component is mounted in the headstock without any play but such that it can rotate, using an adjustable-height insert which is provided with a first scale, the crossbar is provided with a horizontal marking and with a central horizontal second scale, the crossbar is provided with an optically acting surface, whose distance from a plane, which runs parallel to this surface through the center of the retaining hold is defined, the optical component is provided with a marking which allows a mechanical distance measurement to a marking on the measurement bracket and whose distance from the optical axis of the beam path is defined, and the distance between the horizontal marking on the crossbar of the measurement bracket and the center axis of the retaining hole is defined.
Furthermore, a further marking is preferably provided on the optical component, which is located at a defined distance from the zero point of the first scale and whose distance from the optical axis in the direction of the scale is defined.
In one preferred embodiment, the beam path is defined by a telescope, which is used as an optical component and can be focused at different distances, and which preferably has a reticle in order to determine the center.
As an alternative to this, the beam path may also originate from a laser source, which may be in the form of a bar laser or cruciform laser.
Especially for a laser light source, it may be advantageous for the second scale to be in the form of a movable vernier, and for the movable vernier to have a cruciform marking.
The method according to the invention and the measurement devices according to the invention are suitable for determining the conventional parameters of a two-wheeled vehicle frame, namely for determining the frame length, the frame angle, the camber error and the steering head offset. Furthermore, it is also possible to measure the rear twist and the rear offset.
In one preferred embodiment, in order to determine the frame length and the frame angle, the beam path which originates from the optical component is aimed at the optically acting surface at the height of the horizontal marking of the measurement bracket, and the point at which the beam which is reflected from the optically acting surface strikes the first scale is read, and is evaluated in conjunction with the mechanical length measurement between the marking on the optical component and the horizontal marking of the measurement bracket.
In order to determine the camber error, the optical component is aimed at the horizontal marking on both sides of the measurement bracket by adjusting the height of the optical component, and the respective height setting is read on the first scale, and the difference is related to the distance between the measurement points on the two sides.
In order to determine the steering head offset, a mean error in the zero point of the second scale is determined by aiming the optical component at the center of the first scale after which the height of the optical component is moved to the second scale, and the point at which it strikes the second scale is read, the value that is read being corrected by a measurement of the eccentric mounting of the measurement bracket and taking account of any camber error that is found.